1. Field of the Invention
The present invention relates to a method of manufacturing a silicon oxide film.
2. Description of the Related Art
A silicon oxide film is widely used as an insulating film of semiconductor devices such as a semiconductor integrated circuit (IC), and conventionally, a method of depositing a silicon oxide film on a surface of a wafer (substrate) has been examined.
For example, Japanese Laid-Open Patent Application Publication No. 2007-42884 discloses a method of depositing a silicon oxide film by using a vertically extending cylindrical reaction chamber, into which a wafer boat holding a plurality of semiconductor wafers is carried, and after being evacuated and heated, TEOS gas, oxygen gas and hydrogen gas are simultaneously supplied.
However, according to a method of depositing a silicon oxide film disclosed in Japanese Laid-Open Patent Application Publication No. 2007-42884, a reaction gas supplied from a lower part of the reaction chamber such as TEOS gas passes between wafers held by the wafer boat and the reaction gas is supplied to surfaces of the wafers until the reaction gas reaches an exhaust port provided at an upper part of the reaction chamber. In other words, the reaction gas supplied to the wafer surfaces flows in parallel with the wafer surfaces by entering from one end of the wafer, passing a central part and going out of the other end. Because of this, even though the wafer boat is rotated during the film deposition, a silicon oxide film is likely to deposit on an end part and the silicon oxide film sometimes does not have a uniform film thickness between the end part and the central part.
Particularly, in recent years, because a design rule (a width of interconnections in semiconductor circuits) has been miniaturized, depositing an insulating layer having a uniform film thickness on a wafer has been required. Furthermore, cases required to deposit a silicon oxide film on a wafer having a depression that has a small opening and a deep bottom (i.e., high aspect ratio) in its surface have been increasing. In such cases, depositing the insulating film having a uniform film thickness on the wafer was sometimes difficult according to the conventional method. Accordingly, a method of depositing an insulating film having a uniform film thickness without depending on a shape of the wafer surface has been desired.